(1) Field of the Invention
This invention relates to novel synthesized base resins and methods for their manufacture. This invention also relates to compositions used to manufacture laminates where the compositions include commercially available raw resins or a synthesized base resin of this invention as an ingredient. This invention further includes prepregs and laminates manufactured using the compositions of this invention where the laminates are particularly useful in the manufacture of printed circuit boards. The compositions of this invention produce prepregs and laminates that possess excellent electrical performance suitable for high frequency application in electronics, as well as excellent thermal and mechanical performance.
(2) Description of the Art
With operating frequencies of electronic devices ever increasing, the dielectric constant (DK) and dielectric dissipation factor (DF) of the resin substrate used in the printed circuit boards associated with the electronic devices is becoming more important. The lead-free technology in soldering process driven by tighter and tighter environment restriction also requires better thermal stability of the resin substrate. Traditional thermosetting resin systems like phenolic resins and epoxy resins are beginning to show the limitations when incorporated into high dielectric constant and/or high dielectric dissipation factor electronic substrates.
Resins useful in the manufacture of printed circuit boards are disclosed, for example in the following U.S. Pat. Nos. 5,218,030, 5,223,568, 5,571,609, 6,306,963, 6,352,783, 6,617,398 and 7,090,924. Some of the listed patents disclose technology which can produce low DF materials but usually has low Tg and high thermal expansion (although may not be mentioned in the patent). This kind of materials can be used only on double sided or only few layers laminates for high frequency application, like antennas. Some patents disclose technology that can produce a material with high Tg, while their DF is not low enough for very high frequency application. Others disclose technologies that are useful in preparing good final performance products but cannot be used to make dry B-stage glass prepreg for most PCB manufacturers.
The trend of the electronics industry requires materials not only with low DK and DF for high frequency application, but also good mechanical and thermal properties for multilayer board application. High Tg, low thermal expansion and good thermal stability are primary importance for multilayer board application. Therefore, a need continues to exist for thermosetting resin compositions that are useful in manufacturing prepregs and laminates with excellent electrical performance for high frequency application while retaining desirable thermal and mechanical performance like high Tg, low CTE, high thermal stability, as well as low process temperature and being able to make non-sticky, non-tacky B-stage prepreg for conventional multi-layer board fabrication.